Remove stalks and end, rinse the berries in water. Put them in a pan and add just enough water to cover. Bring to a boil and boil for 15 minutes. Press through a sieve, whatever does not go through the sieve put back in the pan again and add a little water, enough to just cover. This time heat but do no boil so vigorously. Press the fruit through a sieve again. Repeat this process one more time. Now most of the fruit should have gone through the sieve leaving only the skins and seeds.